Question

Which of the following produces nitrogen gas after the reaction with nitrous acid?

• A. \( (\text{CH}_3)_3 \text{N} \)
• B. \( \text{C}_2 \text{H}_5 \text{N} \text{C}_2 \text{H}_5 \)
• C. \( (\text{C}_2 \text{H}_5)_3 \text{N} \)
• D. \( \text{C}_2 \text{H}_5 \text{NH}_2 \)

Hint:

When an amine reacts with nitrous acid, it generally leads to the evolution of nitrogen gas, especially for primary amines like \( \text{C}_2 \text{H}_5 \text{NH}_2 \).

Answer 1

The Correct Option is D

The reaction of nitrous acid with primary amines typically produces nitrogen gas. Among the given compounds, ethylamine \( \text{C}_2 \text{H}_5 \text{NH}_2 \) will react with nitrous acid to form nitrogen gas as one of the products. Thus, the correct answer is option (4).

Answer 2

Step 1: Understanding the reaction with nitrous acid
Nitrous acid (HNO₂) reacts with primary amines (R–NH₂) to form diazonium salts, which are unstable and decompose to release nitrogen gas (N₂). This reaction is commonly used to test for the presence of primary amines.

Step 2: Identifying the compound
The compound \( \text{C}_2 \text{H}_5 \text{NH}_2 \) is ethylamine, which is a primary aliphatic amine. Primary amines have one alkyl or aryl group attached to the nitrogen atom.

Step 3: Reaction mechanism
When ethylamine reacts with nitrous acid, it first forms an unstable ethyl diazonium salt intermediate. This intermediate rapidly decomposes, releasing nitrogen gas (N₂) and forming an alcohol or other products.

Step 4: Conclusion
Therefore, \( \text{C}_2 \text{H}_5 \text{NH}_2 \) (ethylamine) produces nitrogen gas upon reaction with nitrous acid, confirming it as the correct answer.